Method for steckel mill operation

Abstract

A method is provided for Steckel mill rolling and finishing flat rolled steel having uniform mechanical properties, good surface quality, and ease of flattening whether in coil form or discrete sheet or plate by hot rolling a heated transfer bar in a Steckel mill and reverse rolling and optional coiling to achieve finished flat rolled product of a selected thickness and selected austenite finishing temperature. The finished product is water cooled to a ferrite transformation temperature and thereafter air cooled until transformation from austenite to ferrite is at least 70% completed. The product may be further water cooled to a temperature below the ferrite transformation temperature.

What is claimed is: 
     
       1. A method for hot Steckel mill rolling and finishing flat rolled steel having uniform mechanical properties, good surface quality and ease of flattening, whether in coil form or discrete sheet or plate, comprising hot rolling a heated transfer bar in a Steckel mill by reverse rolling and optional coiling to achieve finished flat rolled product of a selected thickness and selected austenite finishing temperature prior to any coiling of said finished flat rolled product, water cooling said finished, flat rolled product to a selected ferrite transformation temperature, and thereafter air cooling said finished flat rolled product until transformation from austenite to ferrite is at least 60% completed prior to any coiling thereof. 
     
     
       2. The method of claim 1, wherein said air cooled finished flat rolled product is further water cooled to a temperature below said selected ferrite transformation temperature prior to any coiling. 
     
     
       3. The method of claim 1 or 2, wherein said finished flat rolled product is coiled after runout table cooling. 
     
     
       4. The method of claim 1 or 2, wherein said finished flat rolled product is not coiled after final cooling. 
     
     
       5. The method of claim 1 or 2, wherein said finishing temperature is about 1400°-1650° F. 
     
     
       6. The method of claim I or 2, wherein said finishing temperature is about 1550° F. 
     
     
       7. The method of claim 4, wherein said selected ferrite transformation temperature is 1100° to 1200° F. 
     
     
       8. The method of claim 2, wherein said finished flat rolled product is further water cooled to a temperature of about 1050° F. 
     
     
       9. The method of claim 1 or 2, wherein said water cooling and said air cooling are performed on a short run-out-table. 
     
     
       10. The method of claim 1 or 2, wherein said transformation from austenite to ferrite is at least 70% completed.